[Objective]This study aimed to understand the soil stable organic carbon(SSOC)storage of natural grassland in the hinterland of the Qinghai-Tibet Plateau,and clarify its carbon fixation capacity and potential for increasing sinks.[Method]The soil in the Three-River Source Region was divided according to regional space and three typical grassland types and the active layer soil was taken as the object.The soil total organic carbon(TOC)and Iron(aluminum)-bounded carbon[Fe(Al)-C]were analyzed,the relationship model was established with the geographical and climatic data,and the temporal and spatial variation law in recent 60 years(1961-2020)was retrieved.[Result]The results show that:1)The average content of Fe(Al)-C is 6.07 g·kg-1 and the average content of[Fe(Al)-C]/TOC is 16.87％ in the Three-River Source Region,with obvious zonal characteristics.Also,the content in the central and eastern regions was significantly higher than that in the western region(P＜0.05);2)The contents of Fe(Al)-C and[Fe(Al)-C]/TOC in the three types of grassland were 2.35-8.81 g·kg-1and 11.99％-20.52％,respectively,and the alpine shrub meadow and alpine meadow were significantly higher than those in alpine steppe(P＜0.05).Fe(Al)-C was positively correlated with TOC in the three typical natural grassland types(P＜0.01).3)The results of analog-digital mapping showed that the distribution area change of Fe(Al)-C in the Three-River Source Region has changed in the recent 20 years(2001-2020).Compared with the past two periods;1961-1980 and 1981-2000,the distribution area with its content＞5.75 g·kg-1 and increased by 1.64％ on average.[Conclusion]From our analysis,it was deduced that whole area is in a state of carbon sink,and the C fixation potential of Fe(Al)-C in soils in the Three-River Source Region can not be overlooked.
维普
万方数据